A laser ignition device is known for a combustion engine, according to the Japanese application No. JP20050056267, where on the cylinder head, in its symmetry axis, between the exhaust valve and the suction valve, a multibeam laser in a housing is mounted. In the bottom of the laser housing a series of windows is positioned, through which the laser rays are directed to penetrate into the combustion chamber above the piston, to ignite the fuel mix generated inside the combustion chamber during the suction stroke from the sucked air and the fuel injected by the injector positioned close to one of the valves at an acute angle to the cylinder axis and also at an acute angle to the axis of the adjacent valve. The bottom of the piston also has a recess that constitutes a spherical bowl. The laser is coupled with a control system. Ignition is caused directly by the laser rays that penetrate the space filled with the mixture of fuel and air, at diverse points determined by the positioning of the multibeam laser windows.
Also a laser ignition is known, for a combustion engine, according to another Japanese application No. JP 20050056358, where in the cylinder head, in its axis, between the exhaust valve and the suction valve, a laser housing tube is mounted with a lens system inside and a window at the end. A divided mirror is positioned above the lens system. Control and operation modules are connected to the laser, injector and the suction valve, where the operation module comprises: a laser actuating element, a system for capturing reflected rays, and a system for recording operation irregularities, and the control module comprises the following systems: a laser emission control module, a combustion process monitoring module, and a module for control of the suction valve and the injector. A combustion process monitoring module is connected with cylinder pressure and the connecting-rod angle sensors. The bottom of the piston has a recess in a form of a spherical bowl, and the injector is positioned between the laser housing pipe and the suction valve, at an acute angle to the cylinder axis. The laser rays enter the combustion chamber above the piston, said chamber being filled with a fuel mix obtained from the injected fuel and sucked air during the suction stroke. Ignition is directly caused by a laser ray penetrating the space filled with the mixture of the fuel with air.
A laser ignition instrument is also known for a combustion engine, according to the U.S. Pat. No. 4,416,226, which instrument is built-in with its operation part on the cylinder head at an acute angle relative to the cylinder axis. A stepped sleeve is screwed into the cylinder head, and a further sleeve with a short outer thread is screwed thereinto. In each of the two sleeves, in appropriate seats a lens optic system is mounted, said system comprising a biconvex focusing lens, built in at the end of the sleeve, close to the combustion chamber of the cylinder, and further on, towards the main housing of the pulse laser, there is a plano-convex lens and a biconcave lens are mounted, both of them being embedded in seats with a clearance that accommodates expansion of the lens material. The instrument is connected with a computing module operative basing on the received data concerning the combustion process, ignition setup process and the thermodynamic circulation process in the engine, where the output data from the module flow to a second control module directly connected with a laser, and in this manner the laser operation is performed, in reply to specific signals that characterize the engine operation. Ignition of the fuel mixture is caused directly by a laser beam focused by the lens system at a specific point—a focus within the space of the cylinder combustion chamber.
There is also known a combustion engine and a method of operation a combustion engine with the use of a laser ignition, according to the German patent specification DE 102005056520, also filed under the PCT as WO2006EP66747. In the engine, the fuel injector is built-in within the cylinder head in the cylinder axis or at an acute angle to the axis, and the laser housing us similarly constructed, save that if the laser is positioned at an angle to the cylinder axis, then the injector is positioned centrally, and vice versa. The piston crown has a cavity of a flat base the plane of which 1.5 is perpendicular to the cylinder axis, and the periphery of the cavity is sloped towards outside. In other embodiments the cavity has a centrally positioned hump having an outline of a spherical bowl or the hump is shifted to the left from the cylinder axis or to the right slightly off the axis, and yet in another embodiment, the bottom of the cavity is sloped relative to the cylinder axis, at an angle greater than 90° with the hump aligned with the cavity axis. Correspondingly to the variable shape of the cavity in the bottom of the piston, varies the outline of the space that accommodates the fuel mix: a cake outline, a flat hat outline at the hump aligned with the cavity axis, and a cake outline with a rise at the hump shifted to the left, while with the hump shifted to the right, slightly off the cylinder axis, the outline reminds a shape of a motor car in the cross-section. The injector, suitably to the shape of the outlet: a ring, several outlets for individual streams distributed for example on a circle or in coaxial circles, provides a temporarily variable space comprising the fuel mix. A laser with an end comprising a concave-convex lens generates rays that are converged at a focus positioned always within the space comprising the fuel mix, at a distance from the material of the piston bottom. Ignition is caused directly by the laser ray.